Coke is typically produced by heating coal in a coke oven battery. This battery may have anywhere from 40 to over 100 side-by-side coking chambers or ovens separated from each other by heating walls. Gas is burned within the walls to heat the coal. The floor bricks of each oven rest upon corbels. Below the corbels is an area called the regenerator. The regenerator is filled with bricks that have a relatively large amount of surface area per volume, generally due to slots formed in the bricks. In the regenerator, exhaust waste heat issued to pre-heat incoming air cooling the exhaust waste heat prior to discharge. The slotted bricks are called checkerbricks, and they facilitate the heat transfer from the exhaust waste heat to the combustion materials.
The regenerator supports the corbels. In turn, the corbels support the coke oven floor bricks and the heating walls. The corbels have passageways through which the gas, incoming air and exhaust waste heat are routed from the regenerator to the heating walls and vice-versa. The heating walls, floor bricks, and corbels have traditionally been made of silica brick.
Most coke oven batteries in the United States and, indeed, many throughout the world, are over fifty years old, and are in need of periodic repairs. The silica bricks that make up the oven walls, floors, and corbels begin to degrade as they age due to the cycles of heating and cooling to which they are subjected. Minor repairs are done to keep the ovens operational, and may include repairing the bricks in the ends of the walls, or by replacing the end portions of the walls (end wall repairs). When the degradation of the heating wall becomes severe, the entire wall between two ovens may need to be replaced. In severe cases, the corbel portion of the oven below the oven floor can suffer the same type of degradation as the heating walls of the oven. Cracks may become so large that gas may come out through fractures or the joints between bricks and burn in the regenerator. This results in decreased efficiency and increased operating costs. When this happens, the corbel may need to be repaired or partially or completely replaced.
When the corbel needs to be repaired or replaced, the coking chambers in the immediate vicinity are shut down, and the wall above the corbel and the portion of the corbel which needs replacement are removed. In the past, bricklayers then replace the corbel, or portion thereof, using silica bricks. The process involves hundreds or thousands of silica bricks in a multitude of different shapes, sizes, and arrangements. As there are numerous orifices which are needed to allow gas, air, and exhaust waste heat to flow through the corbel, the silica bricks need to be fit together in a manner similar to a 3-dimensional jigsaw puzzle in order to get the proper shape and configuration of the corbel. This process is labor-intensive and time-consuming. Additionally, each abutment of adjacent bricks creates a joint, and each joint becomes a potential leak point as the wall or corbel begins to deteriorate with use. Because of the large number of bricks used, there are hundreds, and sometimes thousands, of potential failure points in corbels constructed using the conventional techniques and silica bricks.
U.S. Pat. No. 6,539,602 discloses a method of repairing a coke oven wall by using pre-assembled portions of brick. However, although this method could be applicable to repairing corbels, it would have many more joints than the method of this invention and, therefore, would be prone to the same leakage problems over time to which traditional repairs are prone.
Large thermally stable blocks or modules of a non-expanding material with high dimensional stability, good compressive loading and good thermal shock resistance in a range of 0 degrees to 2850 degrees Fahrenheit are shown in U.S. Pat. Nos. 5,227,106 and 5,423,152. These have been developed for endwall repairs, and have recently been used for complete heating wall replacements. Now, it appears that it is also possible to use similar blocks for corbel repairs or replacement. While each set of blocks must be custom-made for each installation, it is still a cheaper and longer-lasting repair than those completed with traditional bricks. In addition, this is a much faster method of effecting the repairs than the traditional method, resulting in less down-time.